The use of revolving drum type condensing units to accumulate cotton lint and to compact the fibers into a more manageable form is a very common practice in the cotton ginning industry. The use of warm humidified air is also used to create an increased moisture level within the confines of the condenser units. The added humidity also increases the efficiency of compaction of these fibers into cotton bales. Textile producers prefer the cotton delivered at approximately an 8% humidity level in order for the cotton to be at an optimum condition for processing in the textile mills.
However, the use of humidified air to increase the moisture level of the cotton fiber creates an additional problem. Not all the humidity is absorbed by the cotton fiber. A substantial amount of the vapor accumulates as condensation on the metal surfaces within the condenser unit. This condensation causes the cotton fiber to adhere to these surfaces, thus accumulations of short fiber and dust block the air flow and hinder the movement of the cotton lint from the condenser unit to the baling press.
Illustrative of the prior art is U.S. Pat. No. 4,140,503, wherein the process of compacting lint begins with the lint fibers entrance into the condenser housing. The arcuate condenser housing converges toward a rotating surface of a perforated drum in the direction of drum rotation. The lint is transported by an air current created by a blower or fan.
The drum is open on at least one end with its cylindrical surface being a screen or perforated material of sufficient grade to prevent the passage of lint fiber into the drum. Air current passes into the drum as a result of a pressure differential created within the drum by the blower or fan which is connected to a discharge duct. The drum rotates about a drum axis and as the air current passes within the drum, the lint fiber carried by such current collects on the surface of the drum.
The rotation of the drum delivers the collected lint to an area within the condenser housing containing a humidifying vent which integrates moisture into the hygroscopic lint as explained in U.S. Pat. No. 4,140,503. The continued rotation of the drum delivers the humidified lint fiber to a doffing chamber. As the lint fiber enters the doffing chamber, a driven first doffing roller compacts the lint fiber against the surface of the vacuum drum forming a sheet of compacted lint fiber hereinafter referred to as a lint batt.
A second doffing roller is located tangent the vacuum drum and is driven in the same rotational direction as the drum. The second doffing roller is equipped with several semi-rigid doffing fins which radially extend from the second doffing roller and displace the lint batt from the drum. The rotation of the second doffing roller directs the lint batt between a pair of driven sealing rollers. A first sealing roller is driven rotationally contrary to the second sealing roller. The doffing chamber is isolated from the outside environment by a combination of the lint batt, the sealing rollers, an upper separating wall and a lower separating wall that join the condenser main housing. An upper sealing gasket and a lower sealing gasket extend from the separating walls to the sealing rollers, forming a seal between the separating walls and the sealing rollers.
Problems occur when, as a result of the humidified air and lint fiber, moisture begins to condense on the drum, separating walls, the sealing rollers, the doffing rollers and the lint slide. The moisture build-up tends to cause the lint fibers to adhere to these surfaces thereby causing blockages and disturbing the integrity of the compacted lint batt.
As the cotton fibers are accumulated, they are fed between the sealing rollers which are slightly biased toward each other by a pair of springs, normally about 50 lb. springs. The biased rollers apply pressure to the moist lint fibers as they are discharged from the condenser, thereby maintaining an air seal while adjusting to varying batt thicknesses. However, if this compacting pressure could be increased at the condensing stage subsequent to increasing the moisture level, when the batt of cotton fiber is relatively thin, the volume of the batt would be reduced, making it easier to alter the flow from one press to another without sustaining substantial back-up in the flow of cotton. Also, the amount of pressure required to bale the cotton with a baling press would be reduced.